The incidence of post cholecystectomy pain (PCP) syndrome at 12 months following laparoscopic cholecystectomy: a prospective evaluation in 200 patients

Introduction

Persistent pain is a well-recognised complication after a variety of surgical procedures [1]. Poorly controlled postoperative pain is an accepted risk factor for persistent postsurgical pain [1], [2], [3], [4]. Laparoscopic cholecystectomy is the gold standard in the management of symptomatic cholecystitis. It is frequently performed as an urgent procedure to reduce the incidence of complications including gall stone pancreatitis [5], [6], [7]. Over 66,000 laparoscopic cholecystectomies are performed in the UK annually [8]. A combination of significant visceral pain from cholecystitis and somatic pain from multiple port site trauma, often results in moderate to severe pain in the first 48 h after surgery [9, 10]. Effective postoperative pain management can be a challenge in this cohort [6].

Persistent pain after laparoscopic cholecystectomy is termed post cholecystectomy pain (PCP) syndrome with a reported incidence of 12–40 % [4, 11, 12]. Current literature appears to focus on visceral pathology as a cause for PCP [9, 13] (Table 1). A potential somatic source for persistent pain is abdominal myofascial pain syndrome (AMPS). It is often poorly recognised and underdiagnosed [14]. Patients who undergo laparoscopic cholecystectomy appear to be at a risk of developing AMPS [9].

The aims of this prospective evaluation were to assess the incidence of poorly controlled postoperative pain in the first 48 h, level of satisfaction with postoperative pain management and the incidence of persistent pain at three, six and twelve months after surgery.

Methods

Adult patients undergoing non-elective laparoscopic cholecystectomy at a tertiary hepato-pancreatico-biliary (HPB) unit were included in a prospective service evaluation. The patient population included those posted in the emergency theatre, who underwent non-elective surgery. They were a mix of patients with acute cholecystitis as well as those with recurrent attacks who were deemed high risk for pancreatitis or presented with gall stone pancreatitis.

This project was registered with the Clinical Audit Safety and Effectiveness (CASE 11216), University Hospitals of Leicester NHS Trust, UK. Written consent was obtained from the patients for telephone review at three, six and twelve months, as well as for the use of de-identified data for analysis and publication. Ethics approval was not required as it was a process audit and service evaluation.

The aim was to evaluate the incidence of poorly controlled postoperative pain relief in the first two days after surgery and patient satisfaction with postoperative pain management. In addition, we wanted to quantify the incidence of persistent pain at three, six and twelve months after surgery. Numerical rating scale (NRS) was used to assess the severity of pain. Poorly controlled postoperative pain was defined as having 5 or more episodes of severe pain (NRS >6/10 at rest or movement) in the first 48 h after surgery [3]. Patient satisfaction was graded as excellent, good, fair and poor. Exclusion criteria included patient refusal to consent for telephone review, conversion to open surgery and presence of learning disability.

Laparoscopic surgery was performed by consultant surgeons or senior surgical trainees. Surgical technique was kept standard and included four ports (epigastric, umbilical and two lateral ports). All patients underwent general anaesthesia. Intraoperative analgesia included intravenous morphine 0.1 mg/kg weight and local anaesthetic infiltration of port sites with 50 mL of 0.25 % levo-bupivacaine. Postoperative analgesia included regular acetaminophen 1 g six hourly, regular codeine 30 mg six hourly and oral morphine 10–20 mg as required on the day of surgery. Patients were discharged on the same day with advice for home analgesics including acetaminophen 1 g six hourly and codeine 30 mg six hourly. Patients were reviewed over the telephone.

The patients were contacted for the first telephone review at three months post-surgery where they were asked the incidence and frequency of poorly controlled pain in the first 48 h after surgery. Patients who complained of persistent pain at three months were subsequently referred to a pain medicine clinic for a review by a pain physician (GN) within 8–12 weeks of the referral. Patients underwent biochemical and radiological investigations to rule out the presence of new onset visceral inflammation including prior to the pain clinic review.

Collected data included age, gender, body mass index, postoperative port site infection and any emergency visit(s) for flare-up of persistent postsurgical pain. Persistent pain was quantified into mild (1–4/10), moderate [5], [6], [7] or severe (>7/10) using a numerical rating scale. Site of persistent pain was grouped into three types (right upper quadrant pain, epigastric pain and periumbilical pain) correlating with the laparoscopic port scars [9].

Results

Over a six-month period between March 2021 and September 2021, 200 successive patients who underwent non-elective laparoscopic cholecystectomy were consented for prospective telephone review. Eleven patients were excluded (conversion to open surgery [6], learning disability [4] and refused to consent [1]). Twelve patients were lost to follow up (6.6 %, 12/189). Patient characteristics and demographic data are provided in Table 2. The incidence of poorly controlled pain in the first 48 h after surgery was 36 % (68/189). Patient satisfaction with perioperative pain management is detailed in Table 2.

Discussion

The incidence of post cholecystectomy pain (PCP) at twelve months was 29 % in this prospective study that included 200 patients. This represents significant morbidity. Over a third of patients (68/189, 36 %) reported poorly controlled post-operative pain. The incidence of PCP was 60 % (41/68) in this subset when compared to the overall incidence of PCP (29 %, 54/189). This reaffirms the possible significance of adequate pain control in the immediate postoperative period [3].

Laparoscopic cholecystectomy is considered an ambulatory procedure. The postoperative pain management can be suboptimal [16, 17]. This cohort carries multiple risk factors for the development of persistent post-surgical pain [9]. These include female gender, obesity, recurrent cholecystitis and pancreatitis [9]. A large proportion of patients (43 %, 81/189) were unsatisfied with the postoperative pain management.

Although PCP is well recognised, the causation appears to be unclear. Majority of the published literature appears to focus on visceral entities. Diagnostic and therapeutic interventions are also primarily directed at ruling out visceral pathologies [9, 13]. In this cohort, a visceral pathology was identified in 25 patients with persistent pain (25/54, 46 %). However, a substantial proportion reporting persistent pain (54 %, 29/54) presented with non-visceral somatic pain. Subsequently this was confirmed as AMPS. There is limited information reported on somatic factors involved in the development of PCP. Chronic pain that arises from the abdominal musculature is termed AMPS, which is a somatic cause of PCP [9, 14]. Patients with cholecystitis who undergo surgery are at a risk of developing AMPS [9]. The underlying pathophysiology is a combination of viscerosomatic convergence and surgical port site trauma. Viscerosomatic convergence is a phenomenon of central and peripheral sensitisation [17], [18], [19], [20]. Patients can suffer bouts of visceral inflammation such as recurrent cholecystitis, pancreatitis or concomitant gastritis. Furthermore, this occurs in a subset of patients with an increased risk of developing persistent pain such as female gender, raised BMI, history of anxiety or depression [9, 21, 22]. Sustained visceral inflammation results in possible sensitisation of the overlying abdominal muscles [14]. Thereafter, the sensitised muscles undergo trauma during port site insertion. Standard port sites include the rectus abdominis (epigastric and umbilical), oblique and transversus abdominis muscles (lateral). In addition, sensitisation of the overlying muscle can be further enhanced by perforation of gall bladder during surgery, biliary leakage, empyema, percutaneous drain insertion or postoperative wound infection [9]. These can result in the development of trigger points in the muscle with subsequent dysfunction and impaired muscle relaxation seen in AMPS [14].

Patients with PCP syndrome often have acute exacerbations. It can result in emergency visits and recurrent hospital admissions [23, 24]. Subsequently, these patients undergo extensive investigations. In a significant proportion of cases, the diagnosis is undetected since a somatic source (AMPS) is rarely evaluated. As a result, patients continue to experience significant distress that results in loss of work and excessive health care utilisation. In our cohort, 48 % of patients with persistent pain (26/54) reported to have emergency hospital visit(s) during the 12-month follow-up period. Among those 26 patients, 21 patients were subsequently diagnosed with AMPS (21/26, 81 %).

In this report, the severity of postoperative pain was pre-defined as NRS >6 based on a previous work on patients undergoing open thoracotomy [3]. The definition for severity of persistent pain was based on published literature [25]. Patients who have undergone laparoscopic cholecystectomy can develop sudden onset of new pain in the upper abdomen (that persists) weeks and months after the surgery, which can be solely attributed to the surgical procedure. We have used the word ‘Persistent’ to denote chronicity.

The authors are aware of the limitation of this study including open label, service evaluation at a single tertiary HPB centre. In addition, data on pre-operative pain and opioid medication use was not collected. This could have helped in tailoring postoperative analgesia. Preoperative screening for anxiety, depression, pain catastrophising were not performed. A formal pain medicine clinic review was possible in 83 % of patients with persistent pain. Outcomes following interventional treatment requires further study as confounding factors include placebo effect, regression to the mean and natural course of this condition.

In conclusion, the provision of effective postoperative analgesia in this cohort of patients is paramount. Future studies should also evaluate pre-operative factor that can influence the development of persistent postsurgical pain. Patients presenting with persistent pain after laparoscopic cholecystectomy should be evaluated for somatic causes, specifically for abdominal myofascial pain syndrome. Further studies are required to confirm these observations.